Conjunctival keloid is a keloid scar that occurs on the conjunctiva, also called conjunctival fibrosis. It is a benign disease in which abnormal wound healing after conjunctival injury or surgery leads to excessive and persistent proliferation of collagen fibers.
Conjunctival keloid is extremely rare. Similar to predisposing factors for skin keloids, it occurs more frequently in individuals with genetic predisposition. Familial cases of conjunctival keloid associated with hereditary keratoconjunctival dystrophy have been reported.
Conjunctival keloid is a benign scar lesion and is not cancer. However, because it can resemble other conjunctival masses such as squamous cell carcinoma or nevus, an ophthalmologic examination (and possibly biopsy) is recommended for accurate differentiation.
Symptoms vary depending on the size, location, and extent of the keloid. Ocular irritation symptoms (foreign body sensation, itching, burning) are often the main complaint. If located near the cornea or on the visual axis, blurred vision or astigmatism may occur. Some patients seek medical attention primarily for cosmetic concerns.
Slit-lamp examination reveals a white to pink raised mass on the conjunctiva. The surface is smooth and hard, with a scar-like appearance. Surrounding conjunctival injection may be present. The lesion commonly occurs near the limbus but can develop anywhere on the conjunctiva.
The exact cause of conjunctival keloid is not fully understood. It is thought to result from an excessive response of the body’s wound healing process.
Surgery/Trauma Related
Pterygium excision: One of the most common triggers
Strabismus surgery: Keloid forms on the conjunctiva at the muscle attachment site
Glaucoma filtration surgery: May occur around the filtering bleb
Ocular trauma: Burns, chemical injuries, mechanical trauma
Inflammation/Genetic Related
Chronic allergic conjunctivitis: Persistent inflammation increases risk
Autoimmune diseases: May occur with chronic conjunctival inflammation
Genetic predisposition: More common in individuals with a tendency for skin keloids
Hereditary keratoconjunctival dystrophy: Familial cases reported
It has been suggested that individuals with genetic predisposition have inherent abnormalities in the cell differentiation process of the limbal region, causing the conjunctival epithelium to exhibit skin-like proliferation1). Cases of conjunctival keloid formation due to chronic mechanical irritation from long-term hard contact lens wear combined with a skin keloid tendency have also been reported2).
The extent, color, surface characteristics, and vascular pattern of the elevated conjunctival lesion are evaluated. Keloids appear as white to pink, hard scar-like masses. Conjunctival keloids can resemble conjunctival malignancies (squamous cell carcinoma, melanoma) in appearance, and cases with a suspicious appearance have been reported 1).
Definitive diagnosis is made by histological examination. Excessive proliferation of collagen fibers and fibroblast proliferation are observed, confirming findings characteristic of keloids. Biopsy is important to rule out malignancy.
| Differential Diagnosis | Key Differentiating Features |
|---|---|
| Conjunctival Nevus | Pigmented, flat, stable |
| Conjunctival Papilloma | Papillary, HPV-related |
| Squamous Cell Carcinoma | Irregular, infiltrative, ulceration |
Squamous cell carcinoma shows irregular, infiltrative growth and requires a different treatment approach from conjunctival keloid, making prompt differentiation essential.
White elevated lesions of the conjunctiva can be caused by various diseases other than keloids, such as pterygium, conjunctival nevus, papilloma, and squamous cell carcinoma. Especially in patients with a history of surgery or trauma and a keloid tendency, conjunctival keloid is possible, but definitive diagnosis requires detailed examination by an ophthalmologist and biopsy if necessary.
For mild symptoms, lubricating eye drops (artificial tears) or eye ointments can relieve eye irritation. The effect on reducing the cyst itself is limited.
Corticosteroids are injected directly into the keloid to suppress inflammation and reduce the size of the lesion. Triamcinolone acetonide (TAC) is commonly used3). Data on skin keloids report that TAC alone achieves 50–100% reduction, with a 1-year recurrence rate of about 33% and 5-year rate of about 50%3).
Excision is considered when conservative therapy is ineffective. Simple excision alone has a high recurrence rate, so combination with adjuvant therapy is important3).
To prevent recurrence after excision, postoperative triamcinolone acetonide injection, cryotherapy (freezing with liquid nitrogen), radiation therapy, and 5-FU combination are used. A meta-analysis of skin keloids reported that TAC + 5-FU has a higher reduction effect (92% vs 73%) than TAC alone3).
Conjunctival keloids are prone to recurrence after surgical excision. Similar to skin keloids, excision alone has a high recurrence rate, so multidisciplinary treatment with adjuvant therapies such as steroid injection, cryotherapy, and radiation therapy is generally recommended.
The pathology of conjunctival keloids is based on mechanisms common to skin keloids. In the wound healing process, fibroblasts are excessively activated, leading to abnormal production and accumulation of type I and type III collagen. In normal wound healing, collagen production and degradation are balanced, but in keloids, this balance shifts toward production.
Keloid tendency shows familial aggregation, and genetic predisposition plays a strong role. Families with conjunctival keloids associated with hereditary corneal dystrophy have been reported, suggesting the possibility of inherent abnormalities in the cell differentiation process of the limbal region.
Chronic inflammation promotes sustained activation of fibroblasts and acts as a promoting factor for keloid formation. Cytokines such as TGF-β enhance collagen production and contribute to abnormal scar formation.
